A piezo electric motor has been known as a so called woodpecker type motor. FIG. 1 shows an essential portion of the woodpecker type motor, wherein four Langevin resonators 1, 2, 3 and 4 of a cylindrical configuration are securedly connected by a bolt 5. Both end faces of the resonators 3 and 4 are vibrated in the axial direction by the application of a high frequency voltage to electrode plates 6 and 7 through terminals 12 and 13. A plurality of bars 8 are slantingly and projectedly secured on the end surface of the rotor 9 which is rotatably supported by a bearing 10. Each free end of the bars 8 is closely opposed to the end surface of the element 4 so that upon vibration of the resonator 4 with the free ends of the bars 8 depressed to the end surface of the resonator 4, the bars 8 are bent in an arcuate configuration, thereby producing a rotational torque on the rotor 9 for rotation of a shaft 11. As the woodpecker type motor rotates pecking the end surface of the resonator 4 by the bars 8, the end surface of the resonator 4 is easily damaged and the bars 8 and the end surface of the resonator 4 are rapidly worn away.